Process of tawing hides or skins



UNITED STATES PATENT OFFICE.

WILLIAM M. NORRIS, OF PRINCETON, NEW JERSEY, ASSIGNOR OF ONE-HALF TOHENRY BURK, OF PHILADELPHIA, PENNSYLVANIA.

PROCESS OF TAWING HIDES OR SKINS.

SPECIFICATION forming part of Letters Patent No. 498,077, dated May 23,1893. Application filed February 3, 1393. Serial No. 460,862. (Nospecimens.)

To all whom it may concern:

Be it known that I, WILLIAM M. NORRIS, a citizen of the United States,and a resident of Princeton, Mercer county, New Jersey, have invented anImproved Process of Tawing or Tanning Hides or Skins, of which thefollowing is a specification.

This invention relates to an improved pro cess of tanning or tawinghides or skins, and consists in first subjecting them to a bath preparedby dissolving in water a metallic salt, such as bichromate of potash,and adding an acid such as hydrochloric acid, and then treating the sameto a bath prepared by dissolving in water a soluble sulphide, such asthe sulphide of potassium or of sodium, and adding an acid such ashydrochloric acid.

In carrying out my process I prepare hides or skins for tawing ortanning by subjecting them to the usual processes of soaking, 1im ing,unhairing, bating, washing, &c. I then place them in a bath prepared bydissolving in water an amount of a metallic salt, such as bichromate ofpotash, equal to about five per cent. of the weight of the hides orskins to be treated therewith, and adding about one half the quantity ofa suitable acid, preferably hydrochloric acid.

The skins are allowed to remain in the above described bath until theyhave thoroughly absorbed the chromium compound, when they are removed,the surplus liquor is pressed out, and the skins thrown into a secondbath. This second bath is prepared by I ash and the hydrochloric acidhas. reached the desired point in its effect upon the skins. This isclearly indicated by achange of color in the skins from a yellowish redto a bluish green. The skins are now removed from this bath and may besubjected to theusual processes of staining, fat-liquoring, coloring andfinishing, as now employed on chrome-tanned stock.

I do not limit myself to the described proportions of ingredients.

I do not claim broadly the tawing of skins by first subjecting them tothe action of a bath prepared from a metallic salt (such as bichromateof potash) and then to the reducing action of hydrogen sulphide, as thatforms the subject of an application filed by me July 14, 1891, SerialNo. 399,448; nor do I claim subjecting the hides or skins to thecombined action of a soluble sulphide, a metallic salt (such asbichromate of potash) and an acid (such as hydro-chloric acid) in thepresence of each other, as that forms the subject of an applicationfiled by Arthur D. Little, June treating the hides or skins to a bath ofa so- I lution of a soluble sulphide, such as sulphide of potassium,with an acid, such as hydrochloric acid, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

WILLIAM M. NORRIS.

- Witnesses:

JOSEPH H. KLEIN, HUBERT HOWSON.

